op baltimore



Aug- 19, 1930. G. H. wHn-TINGHAM coMBE'NsATING THERMOSTAT Filed July 19, 1928 2,1 E l' Il ll Il ll Il Il ami nin Patented Aug. 19, 1930 UNITED STATES PATENT OFFICE GEORGE H. WHITTINGHAM, OF BALTIMORE, MARYLAND, ASSIGNOR TO MONITOR CON- TROLLER COMPANY, OF BALTIMORE, MARYLAND,

A CORPORATION OF MARYLAND COMPENSATING THERMOSTAT Application filed July 19,

This invention relates to a compensating thermostat adapted to be operated by electric current. More particularly, the invention comprises means for insuring accuracy in the operation of the thermostat at all atmospheric temperatures, and structural details which make the device inexpensive to manufacture.

In the accompanying drawing,

Fig. 1 is a front View of the thermostat,

the enclosing tube being shown partly in centra] section;

Fig. 2 is a side View of the thermostat, the tube being shown in central section;

Fig. 3 is a cross section on the line 33 of Fig. l; and, l Fig. 4 is a section on the line 4-4 of Fig. 2.

The thermostat comprises a flat strip 1, of insulating material, having the operating elements secured to its opposite ends, and a tube 2, of insulating material, fits closely around the side edges of the strip, the latter forming a partition Which divides the interior of the tube into tivo compartments. A sheet metal clip 3, of U-form, fits oyer one end of the strip, and this clip or fitting has feet 3fL for attachment to a suitable base 4, and it also has outwardly turned ears 3* and 3 which are perforated to receive a pivot pin 5, which lies in the plane of the strip 1. A

flat metal strip 6 has flanged ends 6a perforated. to receive the pin 5, and this strip is adapted to rock about the pin. member has a boss 6" at one end into which the pivot pin extends, and a contact arm 7 is adjustably mounted upon the boss. As shown, the contact arm is split at one end, and this end is provided with a clamping screw 8, for clamping the contact arm to the boss. A cross-arm 9, of insulating material,

4o is centrally mounted upon the rocking member 6 and extends at right angles to said member and to the pivot pin.

Binding posts 10 and 11 are secured to the opposite ends of the cross-arm and to these binding posts are secured thermally expansible Wires 12 and 13, respectively, which Wires are secured at their opposite ends to a rod 14, which is slidably mounted in a U-shaped bracket 15, the latter being secured to the end of the supporting strip 1, which is oppo- This rocking p 192s. serial No. 293,892.

site the cross-arm. This rod lies and moves in the plane of the supporting strip, the latter being recessed, as shown at 16, to receive the rod. A spring 17, surrounding the rod, is interposed between a Washer 1S on the rod and one arm of the bracket 15, the spring and rod constituting a tensioning device for keeping the thermally expansible Wires taut. A split metal bar 19 fits over and is secured to the lower end of the strip 1, and the bracket 15 is riveted to this bar. The bar has an opening 20, to receive a binding post 21, which is mounted on the base 4.

The tube 2 is detachable and it is provided with a notch 2 at one end so that it may pass upwardly around the fitting 3 to the end of the supporting strip 1.

A flexible conductor 22 electrically connects the sliding rod 14 with the bar 19 which is electrically and mechanically connected with the binding post 21. Thus, the expansible `Wires are electrically connected to said binding post. A flexible conductor 23 is shown connected to the Wire 13, and this conductor passes through a perforation in the cross-arm 9. It it is desired to use the expansible Wire 12 as part of an electric circuit, a exible conductor will be connected to the upper end of the latter Wire.

In operation, the contact arm 7 is set in any desired normal position While the exansible Wires are at atmospheric temperature, and the arm Will not be shifted from normal position except When an electric current is passed through one of the Wires as, for instance, the Wire 13. lVhen this Wire is heated by the current it will expand and the tension device, pulling upon the other Wire, will cause the cross-arm to rock and move the Contact lever. It Will be obvious that the device Will not be affected in its operation by changes in atmospheric temperature. The strip of insulating material Which supports the operating parts of the thermostat forms a partition in the tube Which keeps the heat from the Wire through which the current is passing from affecting the ivire on the opposite side of the partition, and the tube which encloses both Wires shields the Wires from drafts of air Wllil'i might Other- Wise all'ect the temperatures of the Wires unequally.

llf'hut I claim is:

l. j; t iermosto comprising a lint strip of insulating mul'eriul, o. crosserm pw'otzillj.' mounted upon one enfl of 'the strip and projecting' nt opposite Sides of lilie strip, u rod at *elle ouller end of the strip mounted to slide longitudinall;7 thereof, u Sgiing urging said rod away from the cross-mm, and thermally expunsille Wires connecting said rod with opposite ends oi' the cross-arm.

il tliermoelfit Comprising u lzzt strip of insulating material, u Cross-arm pivol'nlly mouned upon oneA encl of the strip und projoeing et opposite Sides of l'lie Strip, u roel at lie other enel of the strip mounted o slide longiuflinally thereof, :i Spring urging' said rocl :moy from the cross-arm, thermally ex- Qnnsible Wires Connecting suicl roel with opposite enfls of die Cross-erin, and u tulle e11- Clos-:ing the strip uno Wii'el.

thermostat comprising :L Hut strip of iuulriino; mueriul, f1 i'ne'gul, port secured. co one enel of the strip and haring bearings in the plane of the strip, :1 rocking member pivorallyY mounted in said bearings, a Contact arm ufljuszioly mounecl on said inen'lber, u Cross-firm seeurecl Centrally *co soicl member A and projecting at opposite scles of the strip, a. tensioning device mounted on the other enel of the srip nml coinprieing n spring preesed rofl sliilalole in the plane of the strip, :mil thermally eipfinsible Wires eonneeing H said rofl with opposite enfle of the Cross-mm.

Ui In teStimon)Y whereof I zillix my signature.

GEGRGE H. VHITTINGHAM. 

